Brake assembly

ABSTRACT

A floating pivot brake assembly suitable for die cast injection molding having variable diameter pivot means mounted on a threaded shank which is accessible for brake adjustments from the outside of the assembly.

ilited States atent Vath [ Aug. 29, 1972 1 BRAKE ASSEMBLY [72] Inventor:William Vath,Massapequa,N.Y.

[73] Assignee: Long Island Mold and Tool Corporation, Westbury, NY.

[22] Filed: Oct. 19, 1970 [21] Appl. No.: 81,906

[52] US. Cl ..188/329, 188/332 [51] Int. Cl ..Fl6d 51/12 [58] Field ofSearch ..l88/329, 330, 331, 332

[56] References Cited UNITED STATES PATENTS 1,994,820 3/1935 Herve..188/332 2,095,808 10/1937 Goepfrich ..l88/331X 1,767,621 6/1930Shields et al 188/329 X FOREIGN PATENTS OR APPLICATIONS 973,248 2/1951France ..l88/329 245,563 l/1926 Great Britain ..188/332 PrimaryExaminer-Evon C. Blunk Assistant ExaminerJohnny D. Cherry Att0rneyRobertR. Strack and James A. Eisenman [57] ABSTRACT A floating pivot brakeassembly suitable for die cast injection molding having variablediameter pivot means mounted on a threaded shank which is accessible forbrake adjustments from the outside of the assembly.

8 Claims, 6 Drawing Figures PATENTEUMIBZE! 912 3.687.246

INVENTOR.

WILLIAM VAT'H FIG. 4

BRAKE ASSEMBLY BACKGROUND OF THE INVENTION 1. Field of the InventionThis invention relates to brake assemblies; and more particularly tofloating pivot brake assemblies which are ideally suited for die castinginjection molding.

2. Description of the Prior Art Friction brakes which operate within abrake drum are well known. Conventionally, such brakes comprise a pairof brake shoes each of which are mounted to pivot at one end as a resultof a camming action applied at the other end. Although apparently nevercommercially adopted, it has also been proposed to have the pivot meansprovided with a radius adjustment in order to efiect what is known as abrake adjustment. Such brake adjustments relate to the generalincreasing of the diameter of the brake shoes in combination so thatthey are closer to the brake drum in their quiescent state. Quiteclearly, it is desirable to adjust brake shoes, or brakes, from outsidethe normally enclosed brake drum chamber. A number of other techniqueshave been developed for doing this, including modification of the springtension normally applied to hold the shoes together.

In the assembly of a brake, it is necessary to insert or install theassembled pair of brake shoes within the brake drum. The initialmounting of the shoes on a backing plate is often a difficult one due tothe fact that strong springs are required and these springs must beproperly positioned in order to hold the shoes in place. The subsequentinstallation of the brakes into the drum may also be difficult becausethe diameter of the shoes, when compressed to their maximum amount, isvery close to the internal diameter of the drum within which they mustfit. In general, this particular problem has been overcome by eitherusing precision made brake linings, or grinding the linings down toinitially fit within the drum. I-Ieretofore, it has been necessary tohold close tolerances.

In the manufacture of brake assemblies, one is also concerned with themetals and the machining steps required. Where one is concerned with theproduction of an economical, yet efficient, brake, it has been found tobe of great advantage to die cast the components. When thismanufacturing technique is employed, the specific design of the brakeassembly must take maximum advantage of the characteristics of thisproduction technique and also may benefit from the uniquecharacteristics made available.

SUMMARY OF THE INVENTION The present invention relates to a brakeassembly specifically designed for production by die casting techniques.Nevertheless, the characteristic features of the invention will be seento be applicable and to advantage in connection with brakes manufacturedin other conventional ways.

It is an object of the present invention to provide an improved brakeassembly.

It is another object of the invention to provide an improved brakeassembly having a floating adjustable pivot for the brake shoes.

It is another object of the invention to provide an improved brakeassembly wherein the floating pivot has a unique structure whereby thebrake may be easily adjusted with conventional tools.

It is another object of the invention to provide a design for animproved brake assembly which does not require the use of costlymachining operations.

It is another object of the invention to provide an improved brakeassembly having a minimum of component elements, each of which may bedie cast.

Another object of the invention is to provide a unique brake assemblywhich may be conveniently assembled with a minimum of labor and specialtools.

In accordance with the invention, there is provided a brake assemblycomprising a backing plate, a pair of shoes arranged end to end anddisposed adjacent to the surfaces of said backing plate, one pair offacing ends of said brake shoes being urged into contact by tensionedmeans and being separated by a pivot means, and the other pair of facingends of said brake shoes being urged apart by cam means; said one pairof facing ends forming opposed substantially conical chambers coaxiallydisposed with adjacent apices, the axis of said substantially conicalchambers being orthogonal to the backing plate. The pivot meanscomprises a pair of elements supported solely by the brake shoes andeach being positioned in surface contact with the walls of one of saidsubstantially conical chambers.

The above objects will be more clearly understood and appreciated, alongwith other objects and the unique features of the invention, from thefollowing detailed description of the invention which is made withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view of a brake assemblyembodying the features of the present invention;

FIG. 2 is a cross-sectional view taken along the lines 2-2 shown in FIG.1;

FIG. 3 is a cross-sectional view taken along the lines 3-3 in FIG. 1;

FIG. 4 is a partial back view illustrating the adjustable pivot meansand pivot slot from the outer face of the backing plate;

FIG. 5 is an elevation view of the right hand brake shoe shown in FIG.I, viewed from the center of the assembly; and

FIG. 6 is an exploded view of the adjustable pivot means provided foradjusting the brakes of the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT The embodiment illustrated inFIGS. 1-5, comprises a brake assembly arranged for seating within abrake drum. The drum is not illustrated. The principal components of thebrake assembly are backing plate 10, a pair of shoes 11 and 12, anactuating cam 13, and adjustable pivot means 14. Springs 15 and 16 arein tension and are mounted in apertures 16, 17 and l8, 19 respectively,located on internally projecting ribs 20 and 21 of the brake shoes. Itwill be appreciated that the position of the cam 13 shown in FIG. 1 isthe unactuated condition of the brake. In order to actuate this brakeassembly, the cam 13 is rotated about an axis through its center. As aresult of such rotation, the cam bears against the faces 22 and 23 ofthe brake shoes, forcing them apart. These shoes accordingly move apart,pivoting about pivot means 14 until brought into frictional bearingcontact with the internal circumference of a surrounding brake drum. Thelocation of surface of such a drum is suggested by dashed line 50.

Each brake shoe has a lining 24 or 25 thereon. The lining may be bondedto a flanged shoe surface in any convenient manner. Its maincharacteristic is its ability to retain its integrity and createfriction upon surface contact with the brake drum.

Cam 13 is connected by means not shown, to an actuating lever 26 whichis rotatable in either a clockwise or counter-clockwise direction. Theoperation of lever 26 is effective to rotate cam 13 about its axis andconsequently is effective to apply the brakes.

The floating adjustable pivot means 14 may be more clearly understoodand appreciated from a study of FIGS. 2-6. Considering FIG. 6 first,there is an exploded view of the pivot means itself. This pivot meansincludes first and second die cast frustum portions 30 and 31, and athreaded bolt member 32. Each portion has a bore therethrough, adaptedto receive bolt member 32 which may include a hexagonal or octagonalhead 35 adapted for engagement by conventional tools. The lower frustumportion 31 includes an axially extended bearing portion 33. Bearingportion 33 is of some predetermined diameter, relative to the width ofpivot slot 51 in the backing plate 10. The significance of thisdimensioning is discussed hereinafter. The lower frustum portion 31 mayhave as an integral part thereof a hexagonal nut suitable for engagementby conventional tools. It is threaded for engagement with the threadedportion 34 of bolt member 32.

Upper frustum portion 30 has oppositely disposed axially extendingradial projections 36 and 37 which coact with the flat surfaces of head35 in order to prevent rotation of frustum 30 relative thereto. Theseprojections 36, 37 extend along the length of the frustum 30 for alimited distance and provide guide means for positioning frustum 30within the aperture formed between the proximate ends of the brake shoesin bearing contact with the pivot means. The bore through upper frustum30 is dimensioned for sliding contact with the unthreaded shank of boltmember 32.

When the pivot means 14 are assembled with a pair of brake shoes, theconical elements 30 and 31 reside within what amounts to a pair ofsubstantially conical chambers. This will be understood most clearlyfrom a consideration of FIGS. 2, 3, and 5. These chambers are formed bythe confronting end faces of the respective shoes. Thus, for example,shoe 12 has an end face 45 with upper and lower cavities therein whichmake up the sector of a cone. The upper cavity 41 appears in the upperright portion of FIG. 2, and the lower cavity 42 appears in the lowerright portion. These cavities are dimensioned to cooperate with thesloping faces of conical portions 30 and 31, respectively. As a resultof the tensioning effect of the springs 15 and 16, the end faces 40 andd of the shoes are forced into bearing contact with the surfaces ofcones 30 and 31. Thus, when the brake is applied, the pivot action takesplace at the interface of these various surfaces.

It will be apparent that frustums 30 and 31 may be adjusted axiallyrelative to one another simply by the tightening, or the advance, of thelower frustum 31 toward the upper frustum 30. This is effected by theapplication of a conventional tool to the integral nut 33. Assuming aright hand thread is employed, clockwise roation of the lower frustumwill result in the advance thereof and the tightening of the brakeadjustment. Conversely, counter-clockwise rotation of integral nut 33will result in the withdrawal thereof and the consequent loosening ofthe brake adjustment.

The remote end of the pivot means containing frustum 31 extends beyondthe backing plate 10 through a pivot slot 51. There is no fixedconnection between the backing plate and the pivot means 14 andaccordingly it is floating, supported only by the brake shoes 11, 12themselves. This fact introduces several important considerations. Itwill be recalled that operation of the brake assembly entails pivotingthe shoes 1 l, 12 about pivot means 14. Although it is advantageous tohave the pivot movable in order to effect centralization of the shoeassembly within the drum, it is extremely important to provide a stablepivot point. These somewhat antithetical requirements are met by theproper dimensioning of the pivot slot 51 in relation to the cooperatingbearing surface 33 of the pivot means.

As shown in FIG. 4, slot 51 is elongated along an axis having a fixedradius, r,,, relative to the center of backing plate 10. The radialwidth 'of slot 51 is only slightly greater than the diameter of thebearing portion 33 of the pivot means. Thus, when the cam 13 isactivated, the pivot point of the brake shoes is a predetermineddistance from the center of the brake assembly and, in this respect, thepivot point is stable. On the other hand, due to the elongation of slot51, the shoe assembly is free to move and centralize within the drum.

Quite obviously, when a floating pivot means is employed, it isadvisable to prevent the separation of the brake shoes 11, 12 from thebacking plate 10, and means must be provided to retain them proximatethereto. These means comprise lugs 5558 which appear in FIG. 1. Theselugs are an integral part of the backing plate and are cast when thebacking plate is originally cast. They are then undercut parallel to thebacking plate surface as illustrated with respect to the lug 56 in FIG.3. The undercut portion 59 is adapted for coaction with a projection 60that is an integral part of the end face of the adjacent brake shoe 12.Thus, the brake shoes are unable to move in a direction perpendicular tothe back plate 10. It is important to note that both projection 60 andthe corresponding projections from the faces of the brake shoes and thelugs 55-58 are integral portions of the members to which they areattached.

Attention is also directed to the lugs 60-63 shown in FIG. 1. These lugsproject perpendicularly from the ribs 20 and 21 of the brake shoes.Their function is to provide a pivot point for the rotation of a springapplying tool while placing springs 15 and 16 into their respectiveapertures in the shoes. With these projecting lugs, one is able toassist the manual assembly of the brake without any extra tool orspecial tool or device.

In order to assemble a brake comprising the components illustrated anddiscussed hereinabove, one initially affixes spring member 16 in theapertures 18 and 13 of a pair of brake shoes. The components are thenseparated sufficiently to fit over cam member 13 and to slip under thelugs 57 and 58. At this time, the shoes are in position against thebacking plate 10. The upper end faces of each shoe are then separatedand pivot means 14 is inserted to place bearing portion 33 within pivotslot 51. When inserted, the shoulder between bearing portion 33 andfrustum portion 31 rests against the inner surface of the backing plate.By further expansion of the brake shoes, the lugs 55, 56 and cooperatingprojections, e.g., 60, on the end faces of the shoes 11, 12

are engaged. Assembly is now essentially completed. It merely remains toposition the unit within the cooperating brake drum. Mention has beenmade previously of the difficulties encountered in the relativelyinexpensive brake units used for small vehicles. These difficultiesinclude the problem that conventional brake linings 24, 25 vary inthickness and consequently the total diameter of the brake assembly mayvary sufficiently to make it virtually impossible to fit within thebrake drum without the ability to reduce the size of the pivot means.This difficulty is completely obviated by the present invention becauseadjustable pivot means 14 can be released to its minimum radial effectin order to permit the brake shoes maximum contraction. It is thus botheasy and economical to provide for the assembly and production ofbrakes.

A specific embodiment of the invention has been shown and described.This embodiment is of particular advantage where one fabricates thecomponents by die casting. On the other hand, a number of the uniquefeatures illustrated hereinabove are applicable to other forms of brakemanufacture. In addition, modification in the various components willbecome immediately apparent to those skilled in the art. All suchmodifications, as embraced in the following claims, are intended to comewithin the scope of the present invention.

What is claimed is:

l. A brake assembly comprising a backing plate, a pair of shoes arrangedend to end and disposed adjacent to the surface of said backing plate,one pair of facing ends being urged into contact by tensioned means andthe other pair of facing ends being urged apart by cam means, said onepair of facing ends forming a pair of opposed substantially conicalchambers coaxially disposed with adjacent apices, the axis of saidsubstantially conical chambers being orthogonal to said backing plate;and a pair of pivot means supported solely by said brake shoes and eachbeing positioned in surface contact with the walls of one of saidchambers, each of said pivot means being a frustum, said frustums beingpositioned with their apices in proximity, one of said pivot meansincluding a substantially cylindrical bearing portion extending axiallyfrom the large diame ter end of said frustum, and comprising anelongated aperture in said backing plate having a width substantiallyequal to the diameter of said bearing portion, the

6 N axis of said elongation being at a fixed radius from a predeterminedpoint within said brake assembly, and said bearing portion beingpositioned within said elongated aperture.

2. A brake assembly in accordance with claim 1, including means formounting said pivot means with their axes coaxial with the axis of saidsubstantially conical chambers, and for adjusting the spacetherebetween, said means being adjustable from the remote surface ofsaid backing plate.

3. A brake assembly according to claim 1, wherein said frustums beingmounted upon a member having threads extending over a predeterminedportion, one of said frustums being in engagement with the threaded 0ion of id member an the other of said frustums ei r ig in sli ingcontact wi th the unthreaded portion thereof.

4. A brake assembly according to claim 1, wherein said one pair offacing ends are separated by at least a predetermined amount and whereinone of said pivot means includes guide means adapted for translationalong the opening defined by said separation.

5. A brake assembly according to claim 4, wherein each of said pivotmeans is a frustum, and said guide means comprise at least oneprojection of substantially constant radial length extending from thesurface of one of said frustums for a predetermined axial length, saidguide means having an arcuate width approximately equal to thepredetermined amount of said separation.

6. A brake assembly according to claim 1, wherein each brake shoeincludes a reinforcing rib extending inwardly therefrom in a positionparallel to said backing plate, said tensioned means being mountedbetween said shoes via apertures on said ribs, and integral projectionson said ribs adjacent to said apertures for mounting said tensionedmeans thereon.

7. A brake assembly according to claim 1, including cooperatingprojections at said one pair of facing ends and on said backing plateextending parallel to the surface of said plate, said projections beingoperative to prevent movement of said shoes in a direction orthogonal tosaid surface.

8. A brake assembly according to claim 1, wherein each of said one pairof facing ends have a pair of depressions on the face thereof, each ofsaid depressions being in the form of a sector of a cone and saidsectors being disposed along a common axis with their apices inproximity.

1. A brake assembly comprising a backing plate, a pair of shoes arrangedend to end and disposed adjacent to the surface of said backing plate,one pair of facing ends being urged into contact by tensioned means andthe other pair of facing ends being Urged apart by cam means, said onepair of facing ends forming a pair of opposed substantially conicalchambers coaxially disposed with adjacent apices, the axis of saidsubstantially conical chambers being orthogonal to said backing plate;and a pair of pivot means supported solely by said brake shoes and eachbeing positioned in surface contact with the walls of one of saidchambers, each of said pivot means being a frustum, said frustums beingpositioned with their apices in proximity, one of said pivot meansincluding a substantially cylindrical bearing portion extending axiallyfrom the large diameter end of said frustum, and comprising an elongatedaperture in said backing plate having a width substantially equal to thediameter of said bearing portion, the axis of said elongation being at afixed radius from a predetermined point within said brake assembly, andsaid bearing portion being positioned within said elongated aperture. 2.A brake assembly in accordance with claim 1, including means formounting said pivot means with their axes coaxial with the axis of saidsubstantially conical chambers, and for adjusting the spacetherebetween, said means being adjustable from the remote surface ofsaid backing plate.
 3. A brake assembly according to claim 1, whereinsaid frustums being mounted upon a member having threads extending overa predetermined portion, one of said frustums being in engagement withthe threaded portion of said member and the other of said frustums beingin sliding contact with the unthreaded portion thereof.
 4. A brakeassembly according to claim 1, wherein said one pair of facing ends areseparated by at least a predetermined amount and wherein one of saidpivot means includes guide means adapted for translation along theopening defined by said separation.
 5. A brake assembly according toclaim 4, wherein each of said pivot means is a frustum, and said guidemeans comprise at least one projection of substantially constant radiallength extending from the surface of one of said frustums for apredetermined axial length, said guide means having an arcuate widthapproximately equal to the predetermined amount of said separation.
 6. Abrake assembly according to claim 1, wherein each brake shoe includes areinforcing rib extending inwardly therefrom in a position parallel tosaid backing plate, said tensioned means being mounted between saidshoes via apertures on said ribs, and integral projections on said ribsadjacent to said apertures for mounting said tensioned means thereon. 7.A brake assembly according to claim 1, including cooperating projectionsat said one pair of facing ends and on said backing plate extendingparallel to the surface of said plate, said projections being operativeto prevent movement of said shoes in a direction orthogonal to saidsurface.
 8. A brake assembly according to claim 1, wherein each of saidone pair of facing ends have a pair of depressions on the face thereof,each of said depressions being in the form of a sector of a cone andsaid sectors being disposed along a common axis with their apices inproximity.